C
* Cable
* Cable Modem
* Cache
* Cache Coherence
* Caddy Drive
* CAM: Content Addressable Memory
* Candela
* Capacitive Keyboard
* CardBus
* Cassette
* CAT1: Category 1 Cable
* CAT2: Category 2 Cable
* CAT3: Category 3 cable
* CAT4: Category 4 cable
* Cat-5: Category 5 Cable
* CAT5e: Category 5e
* CAT6: Category 6 Cable
* CAT7: Category 7 Cabling
* CCD: Charge-Coupled Device
* CD-I Drive: Compact Disc-Interactive Drive
* CD-R Drive: Compact Disk-Recordable Drive
* CD-ROM: Compact Disc-Read-Only Memory
* CD-RW: CD-Rewritable Drive
* Celeron
* Central Processor
* Centrino
* Centronics Interface
* CFM: Cubic Feet Per Minute
* CGA: Color Graphics Adapter
* Chip
* Chipset
* Cinepak
* CIS: Contact Image Sensor
* CISC: Complex Instruction Set Computer
* Clock Rate
* Clock Speed
* Clock Tick
* CMOS: Complementary Metal Oxide Semiconductor
* CNR: Communication and Networking Riser
* Coaxial Cable
* Color Monitor
* Color Printer
* Column Address Strobe
* Common Hardware Reference Platform
* Common Intermediate Format
* CSA: Communication Streaming Architecture
* Compact Flash
* CPLD: Complex programmable logic device
* Composite Video
* Computer Cluster
* Computer Hardware
* Computer Memory
* Concentrator
* Configuration
* Connection Pool
* Connector
* Console
* Continuity Test
* Contrast Ratio
* Control Bus
* Controller
* Conventional Memory
* Coprocessor
* Core Memory
* Counter/Timer
* CPGA: Ceramic Pin Grid Arrays
* CPI: Cycles per instruction
* CPU Time
* CPU: Central Processing Unit
* C-RIMM: Continuity-RIMM
* Crippleware
* Crossover Cable
* Crosstalk
* CRT: Cathode-Ray Tube
* Cryptographic Coprocessor
* CSTN: Color Super-Twist Nematic
* Cursor Control Keys
* Custom-Cut CD
* Cut-Through Switch
Cable
Cable is the physical transmission medium of a group of metallic conductors or optical fibers that are bound together and wrapped in a protective cover, and insulation between individual conductors/fibers and for the entire group.
cable modem
Cable modem provides access of computers to network over cable TV lines. Most cable modems supply a 10 Mbps Ethernet connection for the home LAN. Cable modem achieve higher access speed to the World Wide Web than phone lines using dial up modem or even ADSL modem. The actual performance of a cable modem Internet connection can vary depending on the utilization of the shared cable line in that neighborhood, but typical data rates range from 300 Kbps to 1500 Kbps.
cache
Cashe is a high-speed storage mechanism. It can be either a reserved section of main memory (memory cache) or an independent high-speed storage device (disk cache). A memory cache, also known as a cache store or RAM cache, is a portion of memory made of high-speed static RAM (SRAM). Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM.
cache coherence
Cache coherence is a mechanism for managing the caches of a multiprocessor system so that no data is lost or overwritten before the data is transferred from a cache to the target memory. When two or more computer processors work together on a single program, known as multiprocessing, each processor may have its own memory cache that is separate from the larger RAM that the individual processors will access.
caddy drive
Caddy drive is a type of disk drives that require the media to be placed into a cartridge before insertion into the drive. Other types of disk drives are tray drive and feed drive. The first CD-ROM and CD-R drives were caddy drives, but eventually evolved into tray drives.
CAM: Content Addressable Memory
Content Addressable Memory (CAM) is a special type of computer memory used in certain very high speed searching applications. CAM is designed such that the user supplies a data word and the CAM searches its entire memory to see if that data word is stored anywhere in it. If the data word is found, the CAM returns a list of one or more storage addresses where the word was found (and in some architectures, it also returns the data word, or other associated pieces of data). Thus, a CAM is the hardware embodiment of what in software terms would be called an associative array.
candela
Candela is the International System of Units standard unit of measurement of luminous intensity. The candela is equal to the luminous intensity in a given direction of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and has a radiant intensity in that direction of 1/683 watt per unit solid angle
capacitive keyboard
Capacitive keyboard uses changes in capacitance, or stored static electricity, to register when a user has pressed a specific key on the keyboard. The other type of keyboard called contact keyboard uses changes in flows of electricity to register. Under the keyboard keys of the capacity keyboard are capacitors that store electricity as opposite static charges in pairs of conductive plates made from nickel-plated copper that are separated by a non-conductive material. The opposite static charges hold an attractive field between them, but the insulating material prevents the charges from canceling each other out by coming together. When a key is pressed, the pads move closer to each other and change the capacity for storing a charge, which the keyboard detects as a start or stop in the flow of electricity and inputs the correct keystroke.
CardBus
CardBus is the 32-bit version of the PCMCIA PC Card standard. CardBus also supports bus mastering and operation speeds up to 33 MHz. The CardBus interface supports multiple bus functions which may be implemented in any combination. Use of a bus master function allows the system processor to be offloaded.
cassette
Cassette is a removable magnetic tape storage module that contains supply and takeup reels. Many traditional all audio tapes and videotapes use cassettes as well as backup tape technologies such as DAT, 8mm and Magstar MP.
CAT1: Category 1 Cable
Category 1 cabling (CAT1), one of five grades of UTP cabling described in the EIA/TIA-586 standard, is used for telephone communications and is not suitable for transmitting data.
CAT2: Category 2 Cable
Category 2 Cabling (CAT2), one of five grades of UTP cabling described in the EIA/TIA-586 standard, is designed to transmit data at a speed up to 4 Mbps.
CAT3: Category 3 cable
Category 3 cabling (CAT3), one of five grades of UTP cabling described in the EIA/TIA-586 standard, is a twisted-pair cable with electrical characteristics suitable for carrying 10BASE-T that can transmits data at a speed up to 10 Mbps. IT is discountinued in new network installations.
CAT4: Category 4 cable
Category 4 cabling (CAT4), one of five grades of UTP cabling described in the EIA/TIA-586 standard, is used in Token Ring networks and can transmit data at a speed up to 16 Mbps.
Cat-5: Category 5 cable
Category 5 (Cat-5) is a type of network cabling that consists of four twisted pairs of copper wire terminated by RJ45 connectors. Cat-5 cabling supports frequencies up to 100 MHz and speeds up to 1000 Mbps. It can be used for ATM, token ring, 1000Base-T, 100Base-T, and 10Base-T networking.
CAT6: Category 6 Cable
Category 6 Cable (CAT6) is the 6th generation of twisted pair Ethernet cabling defined by ANSI/EIA/TIA. CAT6 cable contains four pairs of copper wire and all utilized. CAT6 supports Gigabit (1000 Mbps) Ethernet that communications at more than twice the speed of CAT5e. CAT6 is backward compatible with Category 5 cable, Cat-5e and Cat-3. Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard is suitable for 10BASE-T / 100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.
CAT7: Category 7 Cabling
Category 7 Cable (CAT7), defined in ISO/IEC 11801, is a cable standard for 10G Ethernet over 100 meters of copper cabling. Cat7 is backward compatible with traditional CAT5 and CAT6 Ethernet cable. CAT7 features even more stringent specifications for crosstalk and system noise than CAT6 and shielding has been added for individual wire pairs and the cable as a whole. The cable contains four twisted copper wire pairs, just like the earlier standards. CAT7 can be terminated in RJ-45 compatible GG45 electrical connectors which incorporate the RJ-45 standard, and a new type of connection to enable a smoother migration to the new standard.
CCD: Charge-coupled device
Charge-coupled device (CCD) is a device whose semiconductors are connected so that the output of one serves as the input of the next. Digital cameras, video cameras, and optical scanners all use CCD arrays.
CD-I Drive: Compact Disc-Interactive Drive
Compact Disc-Interactive (CD-I), developed jointly by Philips International and Sony Corporation, is a standard for storing video, audio, and binary data on compact optical disks. It supports 552MB of binary data and specifies several different types of video and audio encoding formats. Drives with CD-I technology are called CD-I drives which have a built-in microprocessor to handle many of the computing functions.
CD-R drive: Compact Disk-Recordable drive
Compact Disk-Recordable (CD-R) drive is a type of disk drive that can create CD-ROMs and audio CDs. Recordable CDs are WORM (Write Once, Read Multiple) media that work just like standard CDs. The advantage of CD-R over other types of optical media is that you can use the discs with a standard CD player. The disadvantage is that you can't reuse a disc.
CD-ROM: Compact Disc-Read-Only Memory
Compact Disc-Read-Only Memory (CD-ROM) is a type of read-only-memory compact disk capable of storing large amounts of data. A single CD-ROM has the storage capacity of 1 GB, equivalent to 700 floppy disks. Once a CD-ROM is pressed, new data cannot be stored and the disc cannot be erased for reuse.
CD-RW: CD-Rewritable Drive
CD-Rewritable (CD-RW) drive is a type of disk which allows you to erase discs and reuse them. CD-Rewritable drives are able to write both CD-R and CD-RW discs.
Celeron
Celeron is Intel microprocessor in the Pentium family marketed as a budget/value CPU line. The first Celeron was based on the Pentium II core. Later versions were based on the Pentium III, Pentium 4, and Pentium-M. The main differences between Celerons and Pentiums are in the areas of bus speed and L2 cache features. Both Pentium-II's and -III's ship with 512kB of secondary (L2) CPU instruction cache, which allows the CPU to store recently used instructions close by and is responsible for much of their high performance.
Central processor
Central Processor, also known as central process unit (CPU) or microprocessor, is a silicon chip made from very small transistors and other circuit elements on a single semiconductor integrated circuit (IC). At the heart of all personal computers and most workstations sits a CPU microprocessor. A CPU also controls the logic of almost all digital devices, from clock radios to fuel-injection systems for automobiles. There are many different CPU designs. But in general, the CPU consists of the control unit, the arithmetic and logic unit (ALU) and memory (registers, cache, RAM and ROM) as well as various temporary buffers and other logic. The control unit fetches instructions from memory and decodes them to produce signals which control the other part of the computer. This may cause it to transfer data between memory and ALU or to activate peripherals to perform input or output.
Centrino
Centrino is an Intel marketing brand for a group of CPU, mainboard chipset and wireless network interface for laptop personal computers. The name Centrino is a blend of the words centre and neutrino. Included in the Centrino family are Pentium M processor and an Intel PRO/Wireless 2100(IEEE 802.11b) or dual band 2100a(IEEE 802.11ab) WiFi adapter. New generation of processors are coming out.
Centronics interface
Centronics interface is a standard interface for connecting printers and other parallel devices. For PCs, almost all parallel ports conform to the Centronics standard.
CFM: Cubic Feet per Minute
Cubic Feet per Minute (CFM) is a measurement of the velocity at which air flows into or out of a space, which is used in reference to a computer cooling system, and more typically in reference to an air-cooling system that is supporting overclocking.
chip
Chip is a small piece of semiconductor (usually silicon) on which an integrated circuit is embedded. A computer contains many chips placed on electronic board called printed circuit board.
chipset
Chipset is a group of integrated circuits designed to serve one or more related functions. It is manufactured and sold as a unit, for example, the input/output control chips of a motherboard.
Cinepak
Cinepak is a type of codec (compression/decompression technology) for computer video developed by SuperMac Inc.
CIS: contact image sensor
Contact Image Sensor (CIS), a type of optical flatbed scanner, gathers light from red, green and blue LEDs and directs the light at the original document being scanned. The light that is reflected from the original is gathered by a lens and directed at an image sensor array that rests just under the document being scanned. The sensor then records the images according to the intensity of light that hits the sensor.
CISC: Complex Instruction Set Computer
Complex instruction set computer (CISC) is a microprocessor instruction set architecture (ISA) in which each instruction can execute several low-level operations, such as a load from memory, an arithmetic operation, and a memory store, all in a single instruction. In CISC architecture, the CPU can support as many as two hundred instructions. An alternative architecture, used by many workstations and also some personal computers, is RISC (reduced instruction set computer), which supports fewer instructions.
clock rate
The clock rate of computer is rate in cycles per second (Hz, KHz, MHz) for a computer to performs its most basic operations such as adding two numbers or transfering a value from one register to another. The clock rate of a computer, also know as clock speed, is normally determined by the frequency of a crystal. The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The clock rate of a computer is a useful reference of processing speed between computer chips in the same processor family with the same design architecture: the faster the clock, the more instructions the CPU can execute per second. However, there are many other factors to consider when comparing different computers.
CNR: Communication and Networking Riser
Communication and Networking Riser (CNR), developed by Intel, is a riser card for ATX family motherboards. The CNR specification is open to the industry. It defines a scalable motherboard riser card and interface that support the audio, modem, and network interfaces of core logic chipsets.
coaxial cable
Coaxial cable is a type of cable that consists of a center wire surrounded by insulation and then a grounded shield of braided wire. The shield minimizes electrical and radio frequency interference. The whole thing is usually warpped in another insulation layer and on a outer protective layer. Coaxial cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks.
color monitor
Color monitor is a computer display monitor capable of displaying many colors, while a monochrome monitor can display only two colors -- one for the background and one for the foreground. Most monitors used today for computer systems are color monitors. There are many types of color monitors: CRT, LCD, Flat panel display etc. Color monitors implement the RGB color model by using three different phosphors that appear red, green, and blue when activated. By placing the phosphors directly next to each other, and activating them with different intensities, color monitors can create many colors as controled by the vedio adaptor. The computer's operating system organizes the display screen into a grid of x and y coordinates, like a checkerboard. Each little box on the screen is called a "pixel" (short for "picture element").
column address strobe
Column Address Strobe (CAS) is a signal (or strobe) sent by the processor to a DRAM circuit to accept the given column address. CAS is used with RAS (Raw Address Strobe) and a row-address to select a bit within the DRAM. DRAM stores data in a series of rows and columns and each cell where a data bit is stored exists in both a row and a column. A processor uses CAS and RAS (row address strobe) signals to retrieve data from DRAM. When data is needed, the processor activates the RAS line to specify the row where the data is needed, and then activates the CAS line to specify the column. Combined, the two signals locate the data stored in DRAM.
Common Intermediate Format
Common Intermediate Format (CIF) is a video format used in videoconferencing systems that supports both NTSC and PAL signals. CIF is part of the ITU H.261 videoconferencing standard. It specifies a data rate of 30 frames per second (fps), with each frame containing 288 lines and 352 pixels per line. CIF is used to standardize the horizontal and vertical resolutions in pixels of YUV sequences in video signals. CIF has many variations for different resolutions and technologies.
CSA: Communication Streaming Architecture
Communication Streaming Architecture (CSA), a communications interface technology developed by Intel, directly connects the Memory Controller Hub to the I/O controller hub to eliminate network traffic through the PCI bus. The CSA-based motherboard allows for full-duplex data transmission at gigabit speeds and reduces memory read and write operations latencies because data moves directly from the network interface to RAM. The Intel® 82547EI Gigabit Controller and Intel® 865 and 875 chipsets for the Intel® Pentium® 4 processor form the foundation for CSA-based LOM designs in the CSA based motherboards.
Compact Flash
Compact Flash card is a very small removable mass storage device that relies on flash memory technology. The CompactFlash card is about the size of a matchbook and only weighs half an ounce. There are two types of CompactFlash cards to accommodate different capacities: Type I cards are 3.3mm thick while Type II cards are 5.5mm thick. The card was designed based on the PCMCIA PC Card standard and can fit into a PCMCIA slot with an adapter. CompactFlash technology has resulted in the introduction of a new class of advanced, small, lightweight, low-power mobile products. These products include digital cameras, digital music players, desktop computers, handheld PCs (HPCs), personal communicators, Palm PCs, Auto PCs, digital voice recorders and photo printers.
composite video
Composite video is a type of an analog television (picture only) signal before it is combined with a sound signal and modulated onto an RF carrier. The standards for such signal are NTSC, PAL or SECAM. It is a composite of three source signals called Y, U and V (together referred to as YUV) with sync pulses. Y represents the brightness or luminance of the picture and includes synchronizing pulses, so that by itself it could be displayed as a monochrome picture. U and V between them carry the colour information. They are first mixed with two orthogonal phases of a colour carrier signal to form a signal called the chrominance. Y and UV are then added together. Since Y is a baseband signal and UV has been mixed with a carrier, this addition is equivalent to frequency-division multiplexing.
Computer cluster
A computer cluster is a group of computers that work together closely so that in many respects it can be viewed as though it were a single computer. Clusters are commonly (but not always) connected through fast local area networks. Clusters are usually deployed to improve speed and/or reliability over that provided by a single computer, while typically being much more cost-effective than single computers of comparable speed or reliability.
computer hardware
Computer hardware is the physical components of a computer system, such as CPU, memory, NIC, hard drive, mothrboard etc. On the other hand, computer software is the instruction and programs that tell the computer what to do.
computer memory
Computer memory is a critical part of a computer that retain physical state (data) for some interval of time, even after a computer is powered off. There are many forms of computer memory: RAM, ROM, Cache, Dynamic RAM, Static RAM, Flsh memory, Memory sticks and virtual memory etc. Some of them are embbeded inside a computer, while some are removeable parts.
concentrator
Concentrator, a type of multiplexor, combines multiple channels onto a single transmission channel. A concentrator usually provides communication capability between many low-speed, usually asynchronous channels and one or more high-speed, usually synchronous channels. Usually different speeds, codes, and protocols can be accommodated on the low-speed side.
configuration
In communications or computer systems, configuration is the way a system is set up, or the assortment of components that make up the system. Configuration can refer to either hardware or software, or the combination of both. Often, configuration pertains to the choice of hardware, software, firmware, and documentation. The configuration affects system function and performance.
connector
Connector is a device that connects wires or fibers in cable to equipment or other wires or fibers. Wire and optical connectors most often join transmission media to equipment or cross connects. Most connectors are either male (containing one or more exposed pins) or female (containing holes in which the male connector can be inserted).
counter/timer
In general, a counter is a device which counts (and may display) the number of times a particular event or process has occurred often in relationship to a clock. In practice, there are two types of counters:*up counters which increase (increment) in value*down counters which decrease (decrement) in value. A timer is a specialized type of clock, that can be used to control the sequence of an event or process. Timers can be mechanical, electromechanical, digital, or even software, since most computers have clocks.
A Counter/Timer is a device that performs both functions: counts external events (counter mode) and processor cycles (timer mode). Virtually every microcontroller has one or more on-board counter/timers.
C-RIMM: Continuity-RIMM
Continuity-RIMM (C-RIMM) is a special module used to fill any unused RIMM slots (because there cannot be any unused RIMM slots on a motherboard). It is basically a RIMM module without any memory chips.
crosstalk
Crosstalk is a type of Interference from an adjacent channel or wire, which is caused by electromagnetic interference, along a circuit or a cable pair. A telecommunication signal disrupts a signal in an adjacent circuit and can cause the signals to become confused and cross over each other
CRT: Cathode-ray tube
Cathode-ray tube (CRT) is the technology used in most traditional televisions and computer display screens. A CRT works by moving an electron beam back and forth across the back of the screen. Each time the electron beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, thereby illuminates the active portions of the screen. By drawing many such lines from the top to the bottom of the screen, it creates an entire screenful of images.
cut-through switch
Cut-through switch is a packet switch wherein the switch starts forwarding that frame (or packet) before the whole frame has been received, normally as soon as the destination address is processed. A cut-through switch can achieve the lowest forwarding delays, but it propagates errors from one LAN to another, because errors can only be detected at the end of each frame. In other words, this technique reduces latency through the switch, but decreases reliability.